MECHANICAL AND BIOCHEMICAL-ALTERATIONS OF AORTA INDUCED BY HYDRALAZINE HYPOTENSION

  • 1 January 1980
    • journal article
    • research article
    • Vol. 213  (3) , 514-519
Abstract
Previous experiments from this laboratory indicated that the actomyosin content of aorta from spontaneously hypertensive (SHR) rats was greater than that from normotensive (WKY) rats. The purpose of the present experiments was to determine the effect of hydralazine-induced hypotension on actomyosin content and mechanical properties of aorta from SHR and WKY rats. WKY and SHR rats (10 wk old) were given tap water or tap water containing 80 mg/l of hydralazine for 2 wk and at the end of this time the actomyosin content (sodium dodecul sulfate-polyacrylamide gel electrophoresis), the contractile response to KCl and phenylephrine and the passive stress-strain properties of the aorta were determined. Hydralazine-treated rats had a significantly lower systolic pressure after 1 wk which remained lower for the remainder of the treatment period. Treated WKY and SHR rats exhibited a reduced actomyosin content relative to total protein content or cell number (based on DNA determination). Mechanically, aorta from treated animals showed no change in their passive elastic properties or in their sensitivity (ED50) to either agonist; but the maximum contractile response to both agonists was significantly reduced. Normalization of force development to actomyosin content indicated: that aorta from SHR rats develop less force for a given amount of actomyosin than WKY aorta; a 2 wk period of hydralazine hypotension causes a reduction in force development in both WKY and SHR aorta that can be accounted for by a reduction in cellular actomyosin content and this period of hydralazine hypotension does not return the contractile effectiveness of actomyosin from SHR aorta to that of actomyosin from WKY aorta.

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